First Winter Field Day For The Nashua Area Radio Society

AB1OC Operating at Winter Field Day

AB1OC Operating at Winter Field Day

Source: Our First Winter Field Day – The Nashua Area Radio Society

The Nashua Area Radio Society participated in Winter Field Day for the first time this past weekend. We put up a 40 ft tower and we were QRV on all allowed bands from 160m through 2m and 70cm. Our station was a four transmitter one and we produced a great score during the 24-hour operating period. Winter Field Day presents some unique challenges that we did not encounter during Summer Field Day.

We put together a station for 160m for the first time as well as some other new things. You can read all about our approach to a station and operating for Winter Field Day via the link above.

Fred, AB1OC

160m Portable Antenna System for Field Day

160m Field Day Station Diagram

160m Field Day Station Diagram

The Nashua Area Radio Society tries to do something new each time we engage in an Emcom or other major operation. We decided to try Winter Field Day for the first time this year and we made one of our new elements a capable portable station for 160m.

It’s almost impossible to field an effective 160m station with only a Transmit antenna. Transmit antennas typically are too noisy for effective operation on the low bands. We decided to try a Beverage On The Ground antenna for the receive side of our 160m station. This proved to be a great choice.

Icom IC-7300 Transceiver

Icom IC-7300 Transceiver

We’ve been using the Icom IC-7300 Transceiver almost exclusively for our Field Day stations for the last several years. Many of our members have this rig and its performance and excellent ergonomics make it a great choice. The problem was that we needed a receive antenna input to make the IC-7300 work with our 160m station plans.

INRAD Rx Input Mod for IC-7300

INRAD Rx Input Mod for IC-7300

Fortunately, INRAD came to the rescue with a simple mod for the IC-7300 to add a separate Rx antenna input to the rig.

INRAD Rx Antenna Mod Installation

INRAD Rx Antenna Mod Installation

This mod is simple and is super easy to install. It took me about 30 minutes to do the mod and it worked great. Removed the jumper and you have a separate Rx antenna input. Put the jumper back and the radio performs as stock.

KD9SV Variable Gain Preamp

KD9SV Variable Gain Preamp

Rx antennas typically benefit from the inclusion of a low-noise preamplifier to boost the relatively weak signals from the antennas. We also want a bandpass filter to protect our 160m radio from overload and potential damage which might eliminate from the other transmitters in our Winter Field Day setup. The KD9SV Variable Gain Pre-Amp filled the bill nicely.

KD9SV Front End Saver

KD9SV Front End Saver

We also added a KD9SV Front-End Saver to ground the input to the preamplifier/radio combination when the IC-7300 goes into transmit to further protect the electronics from overload or damage when transmitting on 160m.

KD9SV RBOG Antenna Diagram

KD9SV RBOG Antenna Diagram

We used KD9SV Reversible Beverage On The Ground (RBOG) Transformers to build our receive antenna. The length of the beverage wire is critical in an RBOG setup as an RBOG antenna is a resonant antenna. We used the recommended 180 ft of dual conductor RBOG Antenna Wire to create an antenna for 160m.

RBOG Antenna Kit

RBOG Antenna Kit

An RBOG Antenna such as our must be well grounded at each end. This was accomplished with a pair of 4 ft ground rods and three 50 ft long radials at each end in a crows-foot configuration. All of the need components for the antenna including interconnect and power cables, ground straps, and the electronics were package in a case to keep everything together.

RBOG Antenna Installed In The Field

RBOG Antenna Installed In The Field

The photo above shows one end of the RBOG antenna installed in the Field. You can see both the radials and the feed line transformer attached to one of the ground rods. Our antenna was fed with 300 ft of 75-ohm flooded coax terminated with F connectors. The direction of the antenna can be easily reversed by interchanging the feed line and the 75-ohm terminator at this end of the antenna.

Station Test at our Winter Field Day

Station Test at our Winter Field Day

We decided to set up and test the receive side of 160m station at our Winter Field Day site in advance to work out any installation issues and to gauge the system’s potential performance. Unfortunately, we ended up doing the test in the middle of the day when 160m was basically dead. We also tested the antenna on the AM broadcast band which is just below 160m and we heard 2-3 AM station on every AM frequency in the middle of the day! This was a very good sign of what was to come…

Balun Designs Low-Band Optimized Balun

Balun Designs Low-Band Optimized Balun

We built a 160m dipole for the transmit side of our 160m Portable Station. The heart of this antenna was a Balun Designs Balun optimized for operation on the low-bands. Tuning of the antenna for best operation on the 160m band would have to wait until we had adequate space to set it up at our Winter Field Day site.

160m Transmit Antenna at Winter Field Day

160m Transmit Antenna at Winter Field Day

Setting up our 160m Transmit Antenna was the first order business for the Wire Antenna Team at Winter Field Day. We put up a 50 ft guyed push-up mast used a pull-rope to hoist the 160m Tx Antenna’s Balun to about 48 ft. We used an air cannon to shoot ropes through two tall trees at the ends of the antenna and we were able to get it close to flat-topped.

160m Tx Dipole SWR

160m Tx Dipole SWR

After a little bit of careful tuning, we ended up very pleased with the end result. We had over 60 kHz of usable Tx bandwidth at the bottom of the 160m band. We used the antenna as high as 1.838 MHz during Winter Field Day and it performed great.

So how did the combination perform for us? Well, we made a total of 133 CW contacts on the 160m band during the 24-hour Winter Field Day period with the longest one being to Missoula, MT – a 2,100 mi contact from here in New Hampshire. This is not bad for 100W and portable antennas on Top Band!

Fred, AB1OC

Journey To An ISS Crew Contact

Like many memorable events in our lives, our journey towards the Hudson Memorial School ISS Crew Contact began in a modest fashion with a telephone call from Dan Pooler at Hudson Memorial School in Hudson, NH. Dan had been to Space Camp where he heard about an ARISS Crew Contact from … Continue reading Journey to an ISS Crew Contact →

Source: Journey to an ISS Crew Contact – Nashua Area Radio Society

Our project to help the students at Hudson Memorial School in Hudson, NH make a contact with an astronaut on the International Space Station via Amateur Radio is a memory now. The link above is to an article about the more than year-long journey that led to this once in a lifetime experience. I hope that you enjoy it and don’t miss the video of our contact towards the end of the story.

Fred, AB1OC

A Portable Satellite Station Part 7 – Plans for a 4.0 Station

Portable Satellite Station 3.0 Antenna System

Satellite Station 3.0 Antenna System

We have begun looking ahead to Satellite Station 4.0 and where we want to go next after our ARISS crew contact is complete. Our goals for the Satellite Station 4.0 include:

  • A permanently installed version of our 3.1 Station which can be operated remotely over the Internet
  • Upgraded Transceivers which add Pan Adapter/Waterfall display capabilities
  • Enhancements to our Transportable 2.1 Station for improved performance
  • A more portable version of our 1.1 Station for Grid Square Activations

New 4.0 Station at our Home QTH

The performance of the 3.1 Station’s antennas is very good but the antenna system is a handful to transport. We are planning to install these antennas on a new tower at our QTH and use our Flex-6700 SDR-based Remote Operating Gateway with some upgrades to create a remotely controlled satellite station which can be operated via the Internet. The main components of the 4.0 Station will include:

The new tower will also provide a new antenna system for the 6 m band.

Updated Remote Operating Setup

Flex-6700 SDR-Based Remote Operating Setup

The Flex-6700 SDR and the associated Maestro Remote Unit will enable the 4.0 Station to be remotely operated through the Internet via a Laptop running MacDoppler.

Upgraded Transportable 2.2 Station

Upgrade plans for our Transportable station include the addition of remote switchable polarity relays and a new Icom IC-9700 Transceiver when it becomes available.

Polarity Switch Installed in LEO Pack Antennas

Polarity Switch Installed in LEO Pack Antennas

The polarity switches have been installed on the M2 Antennas 436CP16 and 2MCP8A antennas in our M2 Antennas LEO Pack. We are using a DX Engineering EC-4 console to control LHCP or RHCP polarity selection on the antennas. We have been doing some testing with the upgraded LEO pack which includes the polarity switching capabilities and we are seeing a significant improvement in performance.

Alfa Spid Az-El Rotator

AlfaSpid Az-El Rotator

We are also planning to move the upgraded LEO pack antennas to the current 3.1 Tower to take advantage of the AlfaSpid Rotator which is installed there.

Icom IC-7900 Transceiver

The other major upgrade planned for the 2.2 Station is the new Icom IC-9700 Transceiver when it becomes available. This radio will utilize Icom’s SDR platform and includes a Pan Adapter/Waterfall display which will be a very useful addition for operation with Linear Transponder Satellites.

Upgraded Portable 1.2 Station

We really enjoy mountain topping and activating grid squares so we are planning upgrades to our 1.2 Station for this purpose.

Our 1.2 Portable Satellite Station on Mt. Kearsarge

Our 1.2 Portable Satellite Station on Mt. Kearsarge

The 1.2 Station utilizes computer control to enable operation with linear transponder satellites and will use solar/battery power along with a 100w/70w Icom IC-910H Satellite Transceiver.

Solar Panels

Solar Panels

A pair of 90W foldable solar panels, an MPPT solar charger, and a pair of LiPo 4S4P A123 batteries provide plenty of power to run the IC-910H Transceiver and the associated computer. The portable station also includes a pair of ARR preamps.

Portable Satellite Antenna System

Portable Satellite Antenna System

The antenna system we’ll be using is an Elk Portable Log Periodic 2m/70cm yagi on a camera tripod. A combination of a compass and an angle finder gauge help us to correctly point the antenna.

As you can probably tell, all of these upgrades are in progress and are at various stages of completion. We will post updates here on our Blog as we continue to make progress. Here are links to some of these posts:

Fred, AB1OC

Fall Youth Events at Boxboro and NEAR-Fest

Quite a few Nashua Area Radio Society members have been working on a display to get young people and potential new Hams interested in Amateur Radio. Our display will be part of the New England Amateur Radio Convention in Boxboro, MA on September 8th and 9th. We are also planning a similar display for NEAR-Fest at Deerfield Fairgrounds, NH later in the fall. You can see more about our planned display and the associated hands-on activities via the following link.

Source: Fall Youth Events at Boxboro and NEAR-Fest – Nashua Area Radio Society

I want to share some information about an Amateur Radio event that we will be doing at the Boxboro, MA Ham Radio Convention in September. Our display and hands-on activities provide an introduction to Amateur Radio for young people and include information and a chance to try Amateur Radio activities such as:

You can read more about our plans for the event via the link above.

Morse Trainer Kit

Morse Trainer Kit

We’ve been working with Steve Elliot, K1EL to develop an inexpensive kit building project to include as part of our displays. We will be including a new kit building activity in as part of our display. Builders can purchase the Morse Trainer Kit shown above for $20 and build it at the show. We will provide soldering equipment and kit building mentors to help builders complete their kit. The package includes batteries and a printed manual. We will have these kits available for walk-up purchase at the show on both Saturday and Sunday.

I am also planning to provide forum presentation on the following topics on Saturday at Boxboro:

  • Creating Successful Youth Outreach Projects
  • Portable Satellite Station Design, Operation, and Planning for an upcoming ISS Crew Contact
  • STEM Learning for Young People via High Altitude Balloons Carrying Amateur Radio

You can view the Boxboro Forum schedule here.

I hope to see folks who follow our Blog at the New England at the Boxboro Convention. If you can make it, stop by our display or visit us in the forums and say “hello”.

73,

Fred, AB1OC

 

A 40m High Performance Antenna for Field Day

40m V-Beam Wire Antenna at Field Day

40m V-Beam Wire Antenna at Field Day

The Nashua Area Radio Society has been using a 3-element wire beam antenna for Field Day for the last several years. The antenna uses three guyed 50 ft. fiberglass masts from Max-Gain Systems. The antenna uses three inverted-V style elements separated by a little over 50 ft. Since we are in the northeastern United States, we can point the antenna on a fixed, 260° heading and it covers the entire U.S. well.

40m V-Beam - EZNEC Antenna View

40m V-Beam – EZNEC Antenna View

Our 40m V-Beam antenna was initially designed in EZNEC 5.0. It was manually optimized for decent gain and front to back performance and it worked quite well. Recently, we decided to try automatic optimization software on the antenna as part of a tune-up on the design for Field Day 2018. After looking around on the Internet a bit, we discovered a software package called AutoEZ which looked ideal for my project.

AutoEZ Antenna Modeling and Optimization Software - Wires Tab

AutoEZ Antenna Modeling and Optimization Software – Wires Tab

AutoEZ is a collection of Visual Basic code and Microsoft Excel macros that act as a front-end to EZNEC 5.0 and later. AutoEZ provides a number of very useful enhancements to EZNEC including:

  • Ability to use formulas and variables to construct and modify EZNEC wire models
  • A Test Case generator and execution environment to vary model parameters and graph the results calculations run by EZNEC
  • An automatic optimizer that can adjust the parameters of an antenna model in EZNEC to optimally meet a defined set of performance goals
  • Harnesses the full power of Microsoft Excel formulas for trigonometry, logical, and other mathematical capabilities for use in EZNEC modeling

AutoEZ Antenna Model Variables

AutoEZ Antenna Model Variables

The first step in the project was to rebuild the EZNEC model that I already had for our 40m V-Beam antenna in AutoEZ. I began by defining several AutoEZ Variables and Excel Formulas in the AutoEZ Variables Tab that enabled me to easily modify the design of the antenna and to optimize it. Some of the basic variables included the target design frequency for the antenna, the height and separation of the antenna elements, the distance to the element anchor points, and the length of the element wires.

AutoEZ Antenna Model Variables (Formulae View)

AutoEZ Antenna Model Variables (Formula View)

The image above shows the model variables in “Formula View”. You can see some of the math and trig functions that were used to compute values for some of the variables. AutoEZ can only optimize variables that do not contain formulas so I was careful to ensure that the base separation between the elements and the length of the element wires were constants as these are the parameters that I wanted to optimize later.

AutoEZ Antenna Modeling and Optimization Software - Wires Tab

AutoEZ Antenna Modeling and Optimization Software – Wires Tab

Excel Trig formulas and the Variables were used on the Wires Tab to determine the coordinates of the wires in the antennas. There are a total of 7 wires in the model. Six are the two ends of the three inverted-V elements. The Seventh wire is a short 4″ section in the middle of the Driven Element to allow a current source to be inserted to drive the antenna there. I was careful to create an accurate model of the wire gauge, insulation, and loss that we are using for our V-beam

Model Variables to be Optimized

Model Variables to be Optimized

With the model built, it was back to the Variables Tab to select the parameters to be optimized. Optimization is best done as a multi-pass process and I did this in two steps. The first set of runs included optimization of both the element spacings and their lengths. This led me to conclude that the mast spacing of 27 ft (Driven to Director) and 28 ft (Driven to Reflector) were the best choices. I then set these as fixed values in the variables tab and ran the optimizer a second time with some starting element lengths to optimize the element lengths by themselves.

Optimizer Objectives

Optimizer Objectives

One must create a set of frequencies and objectives for the optimizer before running it. This is done in the AutoEZ Optimize Tab. The antenna is being used for SSB on 40m so I choose a range of frequencies that covered the SSB sub-band on 40m. Note that I weighted the center frequency heavier than the edges by including it more times in the optimizer’s list. The use of the Optimization Objectives and their associated weights and values are well covered in the AutoEZ documentation so I won’t cover them in detail here. The parameters above were chosen to create a reasonable balance between SWR values across the 40m SSB sub-band, good Front/Back and Front/Side performance from azimuth values ranging from 60º to 300º, and a reasonable amount of forward gain for a 3 element antenna of this type.

I expected that the final impedance of the antenna would be a typical value for a yagi in the 20 to 30 ohm range. Thus, I set the SWR calculations based upon a 25 ohm target impedance. More on the matching of the resulting design later…

Element Optimization Results

Element Optimization Results

It took several runs of the optimizer with different sets of Optimizer Objectives to get the final results I was looking for. The Optimizer tried 130 combinations of element lengths to arrive at the final lengths shown above. Note the improvements in SWR (1.6 -> 1.04), Forward Gain (+1 dB), Front/Back (+4.2 dB) and Front/Rear (actually Front/Side) performance that the Optimizer was able to achieve over my manual, trial and error optimization.

Post-Optimization Model Variables

Post-Optimization Model Variables

Next, I rounded the optimized element lengths and plugged them into the Variables Tab.

Post Optimization Azimuth Pattern

Post Optimization Azimuth Pattern

The image above shows the optimized Azimuth pattern for the antenna as generated by AutoEZ and EZNEC. A very clean result!

Post-Optimization Elevation Pattern

Post-Optimization Elevation Pattern

And here’s the optimized Elevation pattern near the center of the SSB sub-band. This antenna is a little low for 40m but the resulting maximum gain at a 35º angle should work well for US contacts during Field Day.

Calculated Performance for the Optimized Antenna

Calculated Performance for the Optimized Antenna

The final step in the optimization process was to calculate a full set of performance calculations for the antenna using the Calculate Tab. AutoEZ makes it very easy to generate a set of Test Cases for incremental frequencies in the SSB sub-band on 40m. Note the setting of the Elevation angle of 35º to match the maximum gain angle for the optimized antenna. Also, note the parameter settings for Ground Type and Characteristics. I set these to model the less than ideal soil conditions that we have here in New England.

Performance Plots for the Optimized Antenna

Performance Plots for the Optimized Antenna

AutoEZ provides several nice graphical capabilities via the Patterns, Triple, Smith, Custom and Currents Tabs.  I used some of them to plot the data from the performance calculations. These graphs help to visualize the results of the optimization to verify that the design objectives for the antenna have been met.

1:2 Matching Balun (25 ohm to 50 ohm)

1:2 Matching Balun (25 ohm to 50 ohm)

I am using a 1:2 matching Balun from Balun Designs at the feed point of the antenna to transform the antennas final 25 ohm feed point impedance to 50 ohm to match our coax feed line.

40m V-Beam Antenna

40m V-Beam Antenna

We are looking forward to using the optimized version of our 40m V-Beam at Field Day 2018. It took me a couple of days of time to read all of the AutoEZ documentation and learn to use the excellent tools it provides. I don’t think I will build another EZNEC antenna model without using AutoEZ. Even without the optimization features, AutoEZ makes the construction and modification of an antenna model in EZNEC far easier than it would be using EZNEC alone. I hope that you’ll give AutoEZ a try for your next antenna design project.

Fred, AB1OC

 

Upgrading our 2.0 Satellite Station for ARISS Contacts

We have been working with Hudson Memorial School near Nashua, NH to prepare for a possible ISS crew contact. The ARISS folks work with schools and their Ham Radio helpers to prepare for these contacts. ARISS provides recommendations for ground station equipment to help ensure a good experience for the students. The ground station recommendations provide a solid set of specifications to support communications with the ISS on the 2m band. The recommendations include things such as:

  • A requirement to build both a primary and a backup ground station
  • Radio and power specifications (a 200W amp is recommended)
  • Antenna specifications including recommendations to provide for switchable LHCP and RHCP
  • Computer controlled azimuth/elevation positioning of antennas to track the ISS
  • Use of a receive preamplifier at the antenna

Portable Satellite Station 3.0 Antenna System

Portable Satellite Station 3.0 Antenna System

We have recently completed construction and testing of our Portable Satellite Station 3.0 which was built specifically to meet the primary station requirements for our ISS contact.

Our plan is to add some upgrades to our Portable Satellite Station 2.0 to create a Portable 2.1 Station which meets the backup station requirements. These upgrades will include:

All of the equipment needed to upgrade our 2.0 Portable Station to 2.1 is either here or will arrive shortly. Here’s some more information on the planned equipment.

Icom IC-910H Transceiver

Icom IC-910H Transceiver

The Icom IC-910H was Icom’s flagship Transceiver for Satellite work before the IC-9100 was released. It’s a very nice satellite radio! Dave, K1DLM graciously lent us his IC-910H for use in our backup station.

Green Heron RT-21 AZ/EL Rotator Controller

Green Heron RT-21 AZ/EL Rotator Controller

We already have a Green Heron Az/El Rotator controller setup for the Yaesu Rotator system on the 2.0 Antenna Tower and we will be reusing it for the 2.1 station.

GHTracker Running On A Raspberry Pi 3

GHTracker Running On A Raspberry Pi 3

We are also planning to build a second Raspberry Pi Rotator Interface for it.

M2 Antenna Systems PS2MCP8A Polarity Switch

M2 Antenna Systems PS-2MCP8A Polarity Switch

M2 Antenna Systems recently added a new 2M polarity switch, the PS-2MCP8A, designed for use with the 2M antenna in their LEO Pack which we are using in our 2.0 Antenna System. We will be installing this relay as well as a PS-70CM polarity switch relay for the LEO pack’s 70cm antenna as part of the 2.1 Antena System upgrade.

DXEngineering EC-4 Control Box

DXEngineering EC-4 Control Box

We will add another DXEngineering EC-4 BCD Control Console to control the polarity switching relays on the upgraded antennas.

m RM ITALY LA-250V Amplifier

RM ITALY LA-250V Amplifier

The final new component in our 2.0 to 2.1 upgrade is the addition of a 200W RM ITALY LA 250 power amplifier. We have opted for the version of this amplifier with the cooling fans. The unit is very well made and we are anxious to see how it performs on the air.

Some of our readers might be wondering what we are planning to do with all of Portable Satellite Ground Station equipment in the long run? We plan on keeping the 1.0 Portable Station for grid square activations and demonstrations. Its simple, battery-powered approach and small antenna make it ideal for this sort of work.

The upgraded 2.0 Portable Station with its enhanced polarity switching will become our transportable station for License Class and Field Day use. It will be converted at the end of 2018 to use our Icom IC-9100 Transceiver that is currently part of the 3.0 station.

We plan to use the Portable 3.0 Station through the year (2018) to support the planned ARISS contact, Field Day, and some demonstrations at local Ham Fests and schools. Once these are complete, we plan to permanently install it here at our QTH and it will become our main satellite ground station at our home QTH.

You can view all of the articles about our Portable Satellite Stations via the links below.

We will begin construction of the 2.1 upgraded station once a few remaining components arrive here. We plan to share some more about the construction and initial testing of our 2.1 Portable Station here.

Fred, AB1OC

A Portable Satellite Station Part 6 – 3.0 Station Initial Contacts

Tech Class First 3.0 Portable Station Test

Tech Class First 3.0 Portable Station Test

With the construction of our Portable Satellite Station 3.0 complete, we’ve been looking forward to an opportunity to test the new setup. We chose the Nashua Area Radio Society’s recent Technician License Class as a good time to both test the new stations and to acquaint our Tech Class grads with one of the many things that they can do with their new licenses – amateur satellite operations.

Tech Class 3.0 Portable Satellite Antenna Test

Tech Class 3.0 Portable Satellite Antenna Test

The first transport of the new 3.0 station antenna system turned out to be simple. The booms and counterweights of the new antenna system are easily separated via the removal of a few bolts located at the cross-boom. This allowed the antennas feed-points, rotator loops and polarity switching connections to be removed and transported as complete assemblies. The separation of the longer-boom antennas into two sections also made transporting the antennas easier and made the antenna elements less prone to bending in transport. Setup and cabling of the new 3.0 antenna system as the class site was quick and simple.

The opportunities to make contacts during our Tech Class were limited but the new system performed well with one exception. We saw a higher than expected SWR readings on the 70cm yagi during transmit. We immediately suspected problems with one of the N connectors that were installed during the construction of the new system (component testing during assembly showed the SWR readings on the 70cm side of the system to be in spec.).

Portable Satellite Station 3.0 Antenna System

Portable Satellite Station 3.0 Antenna System

After the class, we set up the 3.0 system again at our QTH. Transport and re-assembly of the new system are somewhat easier and faster than our 2.0 portable station antenna setup is.

Satellite Antenna System 3.0 Connections

Satellite Antenna System 3.0 Connections

The 3.0 antenna system uses a similar connector bulkhead approach that we used previously. The rotator controls are handled via a single, 8-conductor cable and we have a new connection for the polarity switching controls on the 3.0 system yagis.

Rotator Loop Coax Retention System

Rotator Loop Coax Retention System

We have had some problems with the connections between the preamplifiers mounted at the antennas and the rotator loops which connect the antennas to them. This problem caused several failures in the associated N-connectors on the 2.0 portable antenna system so we fabricated a simple arrangement to prevent the rotation of the antennas from turning the coax inside the N-connectors and causing these failures.

70cm Yagi SWR in the Satellite Sub-Band

70cm Antenna and Feedline SWR in the Satellite Sub-Band

Some isolation tests were performed on each cabling element of the 70cm side of the 3.0 antenna system and this resulted in the location of an improperly installed N-connector. The faulty connector was easily replaced and this corrected the SWR readings on the 70cm side of the antenna system. The image above shows the SWR readings for the 70cm antenna after the faulty connector was replaced. We checked the SWR performance with the 70cm yagi set for both Left-Hand and Right-Hand Circular Polarization and we saw good results in both configurations.

2m Yagi SWR in the Satellite Sub-Band

2m Antenna and Feedline SWR in the Satellite Sub-Band

We also re-checked the SWR performance of the 2m side of the antenna system with the 2m yagi in both polarity settings and it looked good as well.

Portable Satellite Antenna 3.0 Az-El Rotator

Portable Satellite Antenna 3.0 Az-El Rotator

The 3.0 antenna system uses an Alfa-Spid rotator. The Alfa-Spid can handle the additional weight of the larger yagis and has a more precise pointing ability (1° accuracy) which is helpful given the tighter patterns of the larger, 3.0 yagis.

70cm Yagi Switchable Polarity Feedpoint

70cm Yagi Switchable Polarity Feedpoint

The new yagis in the 3.0 antenna system have feed point arrangements which allow the polarity of the yagis to be switched between Left-Hand Circular Polarity (LHCP) and Right-Hand Circular Polarity (RHCP). These antennas used a relay arrangement at the feed-points that flip the polarity of one plane of the yagis by 180° which in turn changes the polarity of the antennas between LHCP and RHCP.

Portable Satellite Station 3.0 Radio and Controls

Portable Satellite Station 3.0 Radio and Controls

With the SWR problem corrected, we set up the 3.0 station radio and controls. The 3.0 station adds our homebuilt PTT Router and the control box from DXengineering which controls polarity switching. Also, the Green Heron rotator control box has been configured to control the new Alfa-Spid rotator.

POrtable Satellite Station 3.0 Computer Control via MacDoppler

Portable Satellite Station 3.0 Computer Control via MacDoppler

We are continuing to use the excellent MacDoppler software to control the 3.0 station. MacDoppler provides tracking controls for the antennas and doppler correction for the Icom-9100 transceivers uplink and downlink VFOs.

Satellite 3.0 Station Control Details

Satellite 3.0 Station Control Details

The image above shows a closer view of the 3.0 station controls. The box in the middle-left with four LEDs and the knob is used to select one of four polarity configurations for the 2m and 70cm yagis – RHCP/RHCP, LHCP/RHCP, RHCP/LHCP, or LHCP/LHCP. Just to the right in the middle stack is our homebrewed PTT Router which expands and improves the PTT sequencing performance of the station. Our station also uses a WaveNode WN-2 for SWR and power monitoring.

So how does the new 3.0 station perform? The new antennas have a tighter pattern requiring careful pointing calibration of the rotators during setup. This is easy to do with the Alfa-Spid rotator. The new antennas have noticeable more gain as compared to the LEO pack used on the 2.0 station. We are also surprised to see how much difference the polarity switching capability makes in certain situations – sometimes as much as two S units (12 dB) in certain situations. The combination of the new antennas and selection of the best polarity combination allows solid operation on many satellites passes with as little as 2 watts of uplink power. We have made a little over 50 QSOs on the new 3.0 station so far and it works great! For more information on the Portable 3.0 Station as well as the 2.0 and 1.0 stations that we’ve built – see the links below:

Fred, AB1OC

 

Receiving SSTV From The ISS

Portable Satellite Station Additions - Digital and Packet

Portable Satellite Station With Additions For Digital and Packet

We’ve recently upgraded our Portable Satellite Station 2.0 to add digital and packet capabilities. The upgrade was pretty simple – we added a SignaLink USB Soundcard and a Windows Laptop PC. Most of the software for packet and digital Amateur Radio communications is written for the Windows OS so using a separate laptop running Windows 10 was the simplest way to go. Another benefit of the second laptop was added screen space to use when doing packet communications via satellites and the International Space Station (ISS).

SSTV Image From The ISS

SSTV Image From The ISS

We recently learned that the ISS was going to be again transmitting SSTV images worldwide. This provided a perfect opportunity to work with the digital additions in our satellite setup. We downloaded and installed MMSSTV on our Windows laptop and set the audio levels on the Windows PC and our SignaLink Sound card to properly receive SSTV signals. The MMSSTV application can decode several different SSTV formats including the PD120 format used by the ISS. The ISS transmits SSTV on a 2m FM voice channel. We configured MacDoppler to track the ISS and perform doppler correction on the 2m ISS 2m downlink and began to listen.

The video above was made during the reception of an SSTV image from the ISS during a pass over the United States. The video gives a good idea of what its like to receive SSTV from the space station.

Another SSTV Image From The ISS

Another SSTV Image From The ISS

We were able to receive several different images from the ISS during the period that it was transmitting SSTV worldwide.

A Third SSTV Image From The ISS

A Third SSTV Image From The ISS

It was pretty easy to capture the SSTV transmissions from the ISS with our Portable Satellite Station 2.0 setup. The signals were strong and I would imagine that the SSTV transmission could have also been received with a simple portable satellite setup with a hand-held yagi antenna.

We hope that the ISS will send SSTV images again in the near future. It was fun receiving them.

Fred, AB1OC

A Portable Satellite Station Part 5 – Plans for Our 3.0 Station

Satellite Grids Worked

Satellite Grids Worked

We’ve made about 250 contacts with our Portable Satellite Station 2.0 and we have worked 106 grids which should be enough to earn a Satellite VUCC. The picture above shows the grids that we’ve worked via Satellites. We’ve learned a lot about satellite operation and had a great deal of fun in the process!

Portable Satellite Station 2.0 Goals

Portable Satellite Station 2.0 Goals

We’ve met all of our original goals for our 2.0 Station and we’ve used it portable at License Classes, Field Day, and other Amateur Radio Demonstrations. We’ve also shared presentations about our 2.0 Station with Amateur Radio Groups here in the New England area. The question that we get most often about the 2.0 Station is “What are your plans for the Portable Satellite Station 3.0”?

Portable Satellite Station 3.0 Goals

Portable Satellite Station 3.0 Goals

Well, here is the plan. We are working with a local group to secure and host an ISS Crew contact. The ARISS folks have published ground station requirements for these contacts. Here are the primary station requirements:

  • Transceiver with 50–100 W output, 1 kHz tuning steps, and 21 memories capable of storing split frequencies
  • Low-loss coax (such as 9913 or LMR-400)
  • Mast-mounted receive pre-amplifier
  • 14-element yagi antenna with switched circular polarity
  • Antenna rotators for azimuth (0–360°) and elevation (0–180°), with an interface for computer control
  • Computer running tracking software for antenna control (including flip mode operation)

Fortunately, our 2.0 Station meets or exceeds almost all of the primary station requirements with the exception of the antennas. The required antenna upgrades will shape the plans for our Portable Satellite Station 3.0.

M2 Antenna Systems 2MCP14

M2 Antenna Systems 2MCP14

ISS Crew Contacts are conducted using 2m Simplex radios on the ISS. We choose the 14-element circularly polarized 2MCP14 yagi from M2 Antenna Systems to meet the ARISS requirements for 2m. Here are the specifications for this antenna:

2MCP14 Antenna Specifications

2MCP14 Antenna Specifications

The 2MCP14 antenna offers a good balance between gain (12.34 dBi) and boom length (10′-6″) and is near the size limit that is practical for use in our Portable Station. This antenna provides an additional 3.14 dBi of gain compared to the M2 Antenna Systems 2MCP8A yagi which we are currently using in the 2.0 Station.

M2 Antenna Systems 436CP30

M2 Antenna Systems 436CP30

While not required for an ARISS Crew Contact, we are also going to upgrade the 70cm yagi to a 30-element circularly polarized M2 Antenna Systems 436CP30 yagi. Here are the specifications for this antenna:

436CP30 Antenna Specifications

436CP30 Antenna Specifications

This antenna is a good match for the upgraded 2m yagi. The 436CP30 has a boom length of 9′-9″ and a gain of 15.50 dBi. This antenna will provide an additional 2.2 dBi of gain compared to the M2 Antenna Systems 436CP16 yagi which we are currently using in the 2.0 Station.

Satellite Antennas Setup Portable

Satellite Antennas Setup Portable

The new antennas will require some modifications to our portable antenna system arrangement. They will need to be mounted on a cross-boom near their centers. As a result, a non-conductive fiberglass cross boom will be required to avoid problems with pattern distortion.

FGCB60 Non-Conductive Cross Boom

FGCB60 Non-Conductive Cross Boom

We will be using an M2 Antenna Systems FGCB60 Cross Boom which has removable, non-conductive end sections made from fiberglass material. The removable ends will make it easier to transport the antenna system. We will also need to make a new mast which is 24″ longer than our current one in the 2.0 Station to create the needed ground clearance for the longer antennas.

Alfa Spid Az-El Rotator

Alfa Spid Az-El Rotator

We are also planning to use a larger Alfa Spid Az-El Rotator. This unit will handle the extra weight of the longer yagi antennas and cross boom assembly and is more precise than the Yaesu unit used on the 2.0 station.

PS-2M and PS-70CM Polarity Switches

PS-2M and PS-70CM Polarity Switches

The last piece of the 3.0 Station Antenna upgrade is to add switchable left-hand and right-hand circular polarity. This will be accomplished via M2 Antenna Systems PS-2M and PS-70CM switchable polarity feed point upgrades for the 3.0 yagis.

DXEngineering EC-4 Control Box

DXEngineering EC-4 Control Box

We have a DXEngineering EC-4 Control Box from a previous project and we can use it to control the relays in the Polarity Switches which will be part of the 3.0 Station antennas. The box will allow us to select any combination of left and right-hand circular polarization on the 3.0 Station uplink and downlink antennas.

We should have all of the parts here for the 3.0 upgrade by the end of the year. We’ll post more as the project proceeds. Other articles in the Portable Satellite Station series include:

You may also be interested in the satellite station at our home QTH. You can read more about that here.

Fred, AB1OC